Understanding Exposure
Photography is all about capturing light. In fact, the etymology of the word “photograph” is basically “light drawing.” To make a photograph that we can see, we have to control both the amount of light that is exposed to a photosensitive surface, be it film or a digital sensor, and also control the sensitivity of that surface to the light. In this series, we will discuss a bit of the physics and characteristics of light and then how a camera and lens combine to control exposure by using what is commonly known as the “Exposure Triangle.”
Shutter speed is a measurement of time that a camera's shutter is open—allowing light, usually after it has passed through a lens and through the aperture diaphragm, to strike a photosensitive surface, like film or a digital sensor.
This article is part of a multi-part series of about photographic Exposure.1. Introduction: The Exposure Triangle2.
ISO, which stands for International Organization of Standards, is a measure of the sensitivity of film or a digital sensor to light.
This article is part of a multi-part series about photographic Exposure.1. Introduction: The Exposure Triangle2. Aperture3.
Aperture is the size of the opening in the lens. Some lenses have fixed apertures, but most photographic lenses have variable apertures to control the amount of light entering the lens. This aperture is regulated by a diaphragm made of overlapping blades that can be adjusted to vary the size of the opening through which light passes. The size of the opening also has a secondary effect on the photograph, as the diaphragm also changes the angle at which the light passes through the lens. We will discuss two "side effects" of changing the